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HAIR   AND   UNDER-FUR

cular arrangement of the individual hairs among mammals;
they are not by any manner of means scattered without order,
but show a definite and regular arrangement, which varies with
the animal. For instance, in an American Monkey (Midas), the
hairs arise in threes—three hairs of equal size springing from the
epidermis close together; in the Paea (Coelogenys) there are in
each group three stout hairs alternating with three slender hairs.
In some forms a number of hairs spring from a common point:
in the Jerboa (JDipusf) twelve or thirteen arise from a single hole;
in Ursus aretos there is the same general plan, but there is one
stout hair and four or five slender ones. There are numerous
other complications and modifications, but the facts, although
interesting, do not appear to throw any light upon the mutual
affinities of the animals. Allied forms may have a very different
arrangement, while in forms which have no near relationship the
plan may be very similar, as is shown by the examples cited from
Ur. Meijerle's paper. The groups of hairs, moreover, have them-
selves a definite placing, which the same anatomist has compared
with the disposition of the bundles of hairs behind and between
the scales of the Armadillo, and which has led him to the view
that the ancestors of mammals were scaly creatures—a view also
supported by Professor Max Weber,1 and not in itself unreason-
able when we consider the numerous points of affinity between
the primitive Mammalia and certain extinct forms of reptiles.2
The hairs are greatly modified in form in different mammals
and in different parts of their bodies. It is very commonly the
case that a soft under-fur can be distinguished from the longer and
coarser hairs, which to some extent hide the latter. Thus the
" sealskin " of commerce is the under-fur of the Otaria if.rsina of
the North. The coarser hairs may be further differentiated into
bristles ; these again into spines, such as those of the Hedgehog
and of the Porcupine. Again, the •flattening and agglutination
of hairs seems to be responsible for the scales of the Manis
1 ** Bemerktmgen iiber den TTrsprang der Haaro," Anat, *4nxf 1893, p. 413.
a See for tills matter, p.  90.    Dr.  Bonavia lias recently advanced (Stitd'i&s -in
JBv&lutivn) Ijondon, 1805) the somewhat fantastic view that the pigment-patches
of Carnivorous and oth-or •mammal** are a reminiscence of an earlier scaly condition.
There i« no direct evldwnco that the primitive mammals wore scaly, nor are the
Monotremaia or Marsupials furninhed with any more traces of stich, a con-
dition titan are other mammals » and they are the most lowly organised of existing
Mammalia.